I don't teach or recommend so-called "purely positive" methods that allow misbehaving pups to continue misbehaving, instead of teaching them which behaviors are and are not allowed. "Purely positive" is fine for teaching tricks and high-level competition exercises, but NOT for teaching the solid good behaviors that all family dogs need to know, and NOT for stopping behavior problems such as barking, jumping, chewing, nipping, chasing, etc.
Though it differs by each individual dog this is the time when most will come up with their own little way of letting you know they’ve got to go. It might be crying at your feet, ringing a bell you’ve set up or waiting at the door — just be sure to pay attention to these signals & follow up. Once your dog knows how to get your attention when he’s got to go you can relax a little and congratulate yourself on a job well done.
The process is the exactly same for older dogs as it is for puppies; prevent accidents from happening by using baby gates and a crate if possible, create a predictable schedule, learn to recognize your dog’s potty signals, accompany your dog outside and immediately reward for all outdoor elimination, properly clean any accidents and supervise your dog until you’re sure that he understands the rules.